The proposed research addresses a fundamental question in biology: how do the environment and genotype interact to produce the phenotype? The pea aphid, an emerging genomic model system, exhibits dramatically different adult phenotypes of winged or unwinged morphs that are induced by environmental conditions in asexual females (a polyphenism) and by a single unidentified genetic locus in males (a polymorphism). Further, genetic variation for the female wing polyphenism segregates with the male wing polymorphism suggesting that the developmental networks underlying the polyphenism and polymorphism are not independent. I propose to (1) map and identify the male polymorphism gene to determine the developmental genetic basis of the male polymorphism, (2) characterize the transcriptional and metabolomic response to wing-inducing stimuli in the asexual females to determine the developmental genetic basis of the female polyphenism and (3) use a systems biology approach to link the results from (1) and (2) to provide a cohesive picture of how environmental signals and genetic signals interact to produce fundamentally similar adult alternative morphologies.